Embodiments of the present disclosure generally relate to methods and devices for managing intracardiac cycle extension through self-learning.
Numerous implantable medical devices exist today that implement a variety of detection schemes and therapies to address various arrhythmias while seeking to promote intrinsic cardiac behavior. An example of an operation mode for a pacemaker represents a DDD pacing mode. In the DDD pacing mode, among other things, a ventricular sensing channel waits for a conducted beat until a programmed atrial ventricular (AV) delay times out. When the AV delay times out without sensing an intrinsic event, the pacemaker delivers a ventricular pacing pulse. When the AV delay is programmed to be relatively short, the pacemaker may deliver ventricular pacing pulses during a relatively large percentage of the cardiac events. The option exists for a physician to program longer AV delays in an attempt to increase the frequency of intrinsic conduction. However, when the AV delay is unduly lengthened, the longer AV delays may introduce complications such as non-physiologic intervals between intrinsic atrial and ventricular events, pacemaker-mediated tachycardia, and artificially limited maximum tracking rates. Consequently, conventional approaches experienced difficulties in managing AV delays to promote conduction without introducing other complications. The foregoing difficulties are also experienced by implantable cardioverter defibrillators (ICDs).
The settings of many sophisticated algorithms in contemporary implantable medical devices that manage a patient's rhythms/arrhythmias can only be modified during office visits/follow-ups. In general, algorithms that manage the patient's rhythms/arrhythmias have no capability for self-adjustment. Consequently, undesired cardiac rhythms may result from the algorithm's behavior due to non-optimized parameters. Examples of algorithms include the ventricular intrinsic preference (VIP) algorithm, managed ventricular pacing (MVP), atrial overdrive pacing and rate adaptive refractory management. The MVP algorithm and VIP algorithm, both seek to minimize ventricular pacing. However, for some patients, the MVP may induce certain nonphysiologic behavior that is difficult to diagnose due to lack of diagnostic information. Pacemaker-mediated tachycardia may result in some patients when algorithms, such as the VIP or MVP algorithms, modified the intracardiac cycle interval (e.g. the AV interval) in an effort to promote intrinsic ventricular activity and to minimize right ventricular pacing.
Given the complexity of an implantable medical device (IMD) today, difficulties have been experienced in attempting to program the IMD to the optimal settings for a patient during implant or during a single follow-up visit. Further, sometimes the IMD may be programmed non-optimally or inappropriately, and may operate in this manner for relatively long periods of time between scheduled follow up visits (which may be from three to six months). Moreover, even when the parameters are set appropriately during implant or follow up, over time, the programmed parameters may become non-optimal when the disease progresses or the patient's underlying rhythm changes. Non-optimal or inappropriate programming may cause patient discomfort and/or may lead to adverse effects.
A need remains for improved methods and devices to manage modification to base intracardiac delay intervals utilized by IMDs when attempting to promote intrinsic physiologic behavior.